The present invention relates generally to a group working system or an electronic conversation system (also referred to as a teleconferencing system). More particularly, the present invention is concerned with a group working system or teleconferencing system which includes a plurality of work stations (terminals) interconnected by a network and in which users located remotely form one another can perform group work (joint work) such as conference, meeting or the like by referencing common materials generated on display screens of the respective work stations.